powerworld tutorial for lmp class -...

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PowerWorld Tutorial

Yen-Yu Lee

The University of Texas at Austin

Jan 18, 2010 Updated December 26, 2012, by Ross Baldick

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Introduction

PowerWorld is one of the most popular power system simulation tools.

Evaluation version can be downloaded at: http://www.powerworld.com/download-purchase/demo-software

Evaluation version can handle up to 12 buses.

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Outline

In this tutorial, we will cover:

Editing a power system model

Running power flow

Solving optimal power flow (OPF)

Showing locational marginal prices (LMP)

Extracting Lagrange multipliers from OPF

Showing contours of LMP

Solving security-constrained OPF

Extracting shift factors

Editing a Power System Model

Open “Model Explorer” under “Case

Information”. All system specifications can be

edited here.

For example, to change the line impedance,

change the “R” and “X” column under “Branches

Input”.

We can also modify an object by right-clicking it

on the one-line diagram.

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Example: editing line parameters

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Example: Adding and Removing

Columns Not all data is displayed in the table by

default.

To Add/Remove a data column, select

“Fields” tab in the Explore Pane.

Select the data column to add/remove,

then click “add->” or “remove <-”.

Note that some columns are editable,

some are read-only.

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Example: Adding the LMP column

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Running Power Flow

To run an AC power flow, simply click the

“Single Solution-Full Newton” under “Tools”

tab.

To run DC power flow, click “Simulator

Options”, and check “Use DC Approximation

…” under the “DC options” tab.

With DC power flow, there should be no

reactive power generated.

Click the “Play” button to show the animation

of power flow. 8

Running power flow

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Play button

Optimal Power Flow

Optimal power flow (OPF) determines the least

cost dispatch of generators considering

transmission constraints.

If we check the option “Use DC Approximation

…” described earlier, DC OPF will be used.

Otherwise, AC OPF is used.

Click “OPF Options and Results …” under “Add

Ons” tab to bring up the “LP OPF Dialog”.

Select “Solution Summary” under “Results”.

Then click “Initialize LP OPF”.

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Solving OPF Click “Solve LP

OPF” to run

OPF, the total

costs is shown

in “Final Cost

Function

Value”.

Showing LMP

Select “Buses” in the “Model Explorer.”

Add the field “Marginal MW Cost” under

“OPF.” (As shown on slide 7.)

The value indicates the marginal cost of

serving one additional unit of demand at a

given bus, which is the locational marginal

price:

See rest of course for details on definition.

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Showing Lagrange Multiplier of

Power Balance Constraint

We can show the Lagrange multiplier that

represents the “shadow price” of each

constraint:

See slides on optimization for definitions.

For the power balance constraint, select

“Area” in the “Model Explorer”.

Add the field “MW Marg. Cost for ACE

Constraint in OPF”, which is the Lagrange

multiplier of the power balance constraint. 13

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Lagrange Multiplier for Power Balance Constraint

Showing Lagrange Multipliers of

Transmission Constraints

Select the “Branches Input” in the “Model

Explorer”.

Add the field “MVA Marg. Cost” under

OPF, which is the Lagrange multiplier of

the binding transmission constraint.

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Lagrange Multipliers for

Transmission Constraints

Extracting Lagrange Multipliers

from LP Solution Details Another way to extract Lagrange multipliers.

Click “OPF Options and Results …” under

“Add Ons” tab to call the LP OPF Dialog.

Select “LP Basis Matrix” under “LP Solution

Detail”.

The data column “Lambda” represents the

Lagrange multiplier of each constraint.

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Extracting Lagrange Multipliers from LP

Solution Details

Showing Contours of LMPs

The “Contouring” function can visualize

various numerical data, such as voltages,

angles, prices, and etc, as color contours.

Click “Contouring” in “Onelines” tab.

Select “Bus” in “Object”, and then select

“OPF\Marginal MW Cost” in “Value”.

Press “OK” to plot contour.

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Plotting LMP

Contours

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Contour map can be

customized by

adjustments in “Contour

Type Options” and

“Custom Color Map”.

The color contour map

can be saved as image

file by right-click on the

onelines, then choose

“Export Image to File”.

Exporting Image to File

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Solving Security-Constrained OPF

Security-Constrained OPF (SCOPF) runs

iteratively between solving an OPF and

running a contingency analysis (CA).

To solve SCOPF, a contingency list must

be defined in advance.

Select “Contingency Analysis” under

“Tools” tab.

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Define CA List

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Click “Insert” under

“Records”.

Click “Insert New

Element” to bring up the

”Contingency Element

Dialog”

Choose the element and

the action type, then

press “OK”.

We could also use Auto

Insert to insert multiple

contingencies at a time.

Manually Define CA List

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Automatically Define CA List

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For example,

generating a

contingency list

with each

contingency

composed of a

single line/

transformer

outage.

Solving SCOPF Click “SCOPF” under “Add Ons” tab.

Enter a value in the “Maximum Number of Outer

Loop Iterations”. For small systems, 10 is usually

sufficient.

Press “Run Full Security Constrained OPF”.

Similar to solving an OPF, we can check the

Lagrange Multipliers for both pre- and post-

contingency constraints at LP solution details.

Again, if we check the option “Use DC

Approximation …” described earlier, DC SCOPF

will be used. Otherwise, AC SCOPF is used.

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Solving SCOPF

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Extracting Shift Factors (Power

Transfer Distribution Factors) Shift Factors represent the sensitivity of power flow on a

given line with respect to power injection at a given

bus/zone and withdrawal at another bus/zone.

Click the “Sensitivities” in “Tools” tab. Select “TLR

Sensitivities / Generation Shift Factors”.

Choose “Multiple Element” in “Device Type”. Select the

line or transformer we are interested in the dialog

brought up by clicking “Select Lines/XFMR”.

Transactor type “Seller”/”Buyer” calculates the

sensitivities with respect to injecting/withdrawing power.

Press “Calculate TLR Sensitivities.”

Power transfer distribution factors represent the

sensitivity of power flow for injection at a given bus and

withdrawal at the slack bus. 28

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Extracting Shift Factors

Shift Factors of line

1-2 with respect to

injection at bus 2

Saving Data into Excel/CSV

Data shown in a table can be saved into a

Excel or csv file.

Right-click on any table, move cursor on

“Copy/Paste/Send”, and select “Send All

to Excel”. A Excel spread sheet will be

brought up.

Or, Right-click on the table, move cursor

on “Save As”, and select the desired

format.

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Summary

Editing a power system model

Running power flow

Solving optimal power flow (OPF)

Showing locational marginal prices (LMP)

Extracting Lagrange multipliers from OPF

Showing contours of LMP

Solving security-constrained OPF

Extracting shift factors

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